Defined Benefit Plans - Defined Benefit Plans Narrative (Details) - Pension Plans, Defined Benefit [Member] $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 1.7	$ 2.8
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	$ 3.4	$ 3.4